The present invention relates to a method of identifying a thickness of a metal laminate gasket and a gasket with a plate information device, so that a kind or a thickness of a gasket is readily recognized after the gasket is assembled.
Recently, efficiency of an engine has been significantly improved. Since a top clearance between a piston at a top dead center and an inner top portion of a cylinder head affects power and exhaust gas of the engine, a required top clearance has been precisely examined and selected for a particular engine.
A top clearance is generally determined when an engine is designed. However, since a cylinder head gasket is installed between a cylinder head and a cylinder block, a precise adjustment of the top clearance is made by selecting the thickness of a cylinder head gasket.
On the other hand, when a new engine is developed, a huge amount of money is required. Therefore, in order to efficiently utilize the engines, the same engines are used for different models of cars. In this case, the engines are slightly modified to suit the respective models. The top clearance of the engine may be changed by adjusting the thickness of a gasket.
In a metal laminate gasket, the gasket is formed of a plurality of metal plates. When the thickness of the engine is changed for the reason as stated above, therefore, one of the metal plates with a certain thickness is changed to another plate with a different thickness. Thus, the gaskets with the different thicknesses are prepared for one type of the engine. In the same gasket, a plurality of plates with different thicknesses is prepared and selectively used according to the models of the cars.
Before a gasket is assembled, it is easy to identify or recognize the plates by making signs on them. However, after the gasket is assembled, since the outer configuration of the gasket is substantially the same in all the gaskets, it is very difficult to recognize the plate used in the gasket or identify the gasket, because the plate to be changed is not seen well from outside, i.e. sandwiched between upper and lower plates.
In U.S. Pat. No. 4,648,607, a steel laminate gasket with assembly order identification device is disclosed, wherein each plate is provided with specific projections. In case the projections align in a specific order, the order of assembly is correct. Therefore, assembly order can be identified by checking the projections after the gasket is assembled.
However, in this patent, the respective plates must have the projections to identify the plates. Since the respective plates have different projections, different cutting devices are required for preparing the respective plates. Therefore, this method is not proper or practical.
In Japanese Patent Publication (KOKAI) No. 3-255275 published on Nov. 14, 1991, a gasket includes a plurality of metal plates, and checking sections formed on the metal plates, number of which is equal to that of the metal plates. Lights are emitted to the respective checking sections to ascertain the order of the assembly of the plates.
In Japanese Utility Model Publication (KOKAI) No. 1-165857 published in 1989, a gasket is formed of a sheet material with a desired thickness and a combination plate with a fixed thickness. The sheet material includes one or more notches based on a thickness of the sheet material. The number of the notches can be seen through one large notch formed on the combination plate when the sheet material and the combination plate are assembled.
In the above Japanese Utility Model publication, a kind of a gasket can be recognized by watching the gasket. However, there has not been proposed to easily identify a kind of a gasket by an automatic mechanical system.
Accordingly, one object of the invention is to provide a method of automatically identifying a kind or a thickness of a metal laminate gasket.
Another object of the invention is to provide a method as stated above, which can be easily performed without using sophisticated mechanism.
A further object of the invention is to provide a metal laminate gasket, which can be easily identified by a mechanical method after the gasket is assembled.
A still further object of the invention is to provide a metal laminate gasket as stated above, which can be manufactured easily and economically.
Further objects and advantages of the invention will be apparent from the following description of the invention.